Replacement drive installed. No rebuild?

Good morning.

Monday, my 5D experienced a drive failure. Over the last 5 years, this is about the third or so (most within the last 3 months which I’ve expected as the drives are all same age and get older).

This morning, the data protection finished (after 36 hours or so) and I physically pulled the dead 6TB and installed a new 8TB drive. No problems there.

Maybe I’m thinking too much, but I expected the Drobo to go back into Data protection mode to spread the existing data back across all the drives for protection. Instead, after the first two minutes or so, the drive light just went green, it says “good” and there’s no more activity.

Is this normal???